The Institute of Electrical and Electronics Engineers (IEEE) standard 802.15.6 and The European Telecommunications Standards Institute (ETSI) technical committee “SmartBAN” define physical and medium access control specifications for packet-based short-range communications in wireless body area networks (WBANs). WBANs target e.g. medical and healthcare monitoring systems in the vicinity of a human body, or inside the human body.
Standard [1], i.e. IEEE standard 802.15.6-2012, “IEEE Standard for Local and metropolitan area networks - Part 15.6: Wireless Body Area Networks”, IEEE Computer Society, LAN/MAN Standards Committee, Feb. 29, 2012 discloses a standard for short-range, wireless communication in the vicinity of, or inside, a human body (but not limited to humans). The communication networks use existing industrial-scientific-medical (ISM) frequency bands as well as bands approved by national medical and/or regulatory authorities. MAC frame formats, MAC functions, security services, and physical layer specifications are discussed in this standard covering Wireless Body Area Networks.
Standard [2], i.e. Smart Body Area Network (SmartBAN), “Enhanced Ultra-Low Power Physical Layer”, ETSI TS 103 326 V1.1.1, April 2015 discloses ETSI specifications for ultra-low power physical layer of the SmartBANs. It further applies to short-range, wireless communication between wearable sensors or devices and the hub coordinator, and it specifies the physical layer for transmitting on the medium. Packet formats, modulation and forward error correction (FEC) algorithms are discussed.
Standard [3], i.e. Smart Body Area Network (SmartBAN), “Low Complexity Medium Access Control (MAC) for SmartBAN”, ETSI TS 103 325 V1.1.1, April 2015 discloses the MAC protocol specification designed to facilitate spectrum sharing with other devices. It comprises channel structure, MAC frame formats and MAC functions and the operative frequency band is the ISM frequency band from 2.4 GHz to 2.4835 GHz.
The above three standards [1]-[3] provide merely some hints for implementing the mechanisms described in the present invention. They provide the means to modify super-frame related allocations and parameters in limited ways. More specifically, standard [1] does not allow data communications between Hubs. Standard [1] has an optional mode for multiple WBANs to coexist in the same radio channel. The Hubs may exchange specific control messages to align their active periods so that they do not overlap. This potentially requires super-frame reallocations from both coexistent WBANs. It is meant for coexistence purposes only. It enables modification of channel access periods, but not super-frame duration modifications on super-frame-by-frame basis. Standards [2] and [3] provide the possibility to change inter-beacon interval (i.e. IBI) on a super-frame-by-frame basis, but they do not provide any specifications for realignment of the IBI.
Wireless network research has identified over the years various mechanisms for realigning super-frames, such as the following references [4]-[8]:                Draft Standard [4]: “P802.15.8 / D4, Draft Standard for Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Peer Aware Communications (PAC), March 2017”        Reference [5]: Muthukumaran P., de Paz R., Spinar R., Pesch D., “MeshMAC: Enabling Mesh Networking over IEEE 802.15.4 through Distributed Beacon Scheduling”, Ad Hoc Networks (ADHOCNETS 2009). Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, vol 28. Springer, Berlin, Heidelberg, 2010        Reference [6]: H. Shabani, M. M. Ahmed, S. Khan, S. A. Hameed and M. Hadi Habaebi, “Smart Zigbee/IEEE 802.15.4 MAC for wireless sensor multi-hop mesh networks,” 2013 IEEE 7th International Power Engineering and Optimization Conference (PEOCO), Langkawi, pp. 282-287, 2013        Reference [7]: B. H. Lee and H. K. Wu, “Study on a Dynamic Superframe Adjustment Algorithm for IEEE 802.15.4 LR-WPAN,” 2010 IEEE 71st Vehicular Technology Conference, Taipei, pp. 1-5, 2010        Reference [8]: M. Bennis and J. Lilleberg, “Inter Base Station Resource Sharing and Improving the Overall Efficiency of B3G Systems,” 2007 IEEE 66th Vehicular Technology Conference, Baltimore, Md., pp. 1494-1498, 2007        
However, all of the proposed mechanisms aim at improving the channel resource utilisation of the existing wireless network, and not for aligning individual networks to enable communications between such networks. The draft standard [4] explicitly establishes peer-aware communications groups and establishes an overlay cyclic-super-frame structure with clearly defined periods for synchronisation, discovery, and peering. Potentially any device can be a member of such group, not only hubs, but there are no specifications, how an existing hub coordinated network and an overlay cyclic-super-frame coexist. Furthermore, there are no specifications for realignment of these kinds of different networks, which is the subject-matter of the present invention.
Summarizing the starting point of the present invention, the main problem in the prior art is thus that neither the fore-mentioned IEEE nor the ETSI standards provide a solution for super-frame realignment of WBAN networks using the same standard specifications in near vicinity.